Once an infant begins to turn his head with neck extension, suckling becomes an active oral pattern with large up and down and forward/back movements of the jaw; and rhythmic forward/back movement of a cupped tongue. The newborn's respiratory function is characterized by obligatory nasal breathing because of the close approximation of the tongue to the soft palate and posterior pharyngeal wall, which can obstruct oral airway patency.
The perioral region is richly supplied with neural mechanoreceptors capable of inducing the tissue changes associated with movements of the lower face (Barlow 1991).
Human lip muscles display excitatory reflex responses. Particular attention is directed to the obicularis oris, buccinators muscles, mentalis muscles and underlying bone as being supportive/resting areas of the pacifier shield.
Oral shields are commonly used in applications such as pacifiers, teethers, feeding devices and sippy cups. Shield designs (Panicci, U.S. Pat. No. 4,403,613 and Uehara, U.S. Pat. No. 6,767,357) disclose the lower part of the shield slightly curving away from the face. The Panicci design is not sufficiently offset to allow for free forward posturing of the mandible. Additionally, Panicci does not recognize the need to be supportive only on upper arch, and is not designed based on available anthropometrics. Panicci (in contradiction to the present invention) will intensify the sensory and motor components against the lower lip and contribute a retrusive stimulation and force against the mandible and other areas below the upper arch and intermaxillary space. This reflex will actually cause more restriction of the upper airway.
The relative magnitudes of lip-muscle reflex components are known to vary in a systematic manner with the stimulation of the lip muscle and site of stimulation.
Current designs of pacifier baglets (to be differentiated from the pacifier shield) claim benefits to orthodontic development, particularly of the maxillary arch. These designs are often paired with different oral shields for corresponding size or marketing purposes. Beyond these claims of orthodontic benefits, pacifiers have also been shown to reduce the incidence of SIDS (Sudden Infant Death Syndrome). The mechanism of this protection is believed to be in the maintenance of a patent oral airway during infant sleeping in a supine position and pacifier sucking. It has been hypothesized that the association of pacifier use with reduced risk of Sudden Infant Death may be mediated by forward movement of the mandible and tongue. Pacifier use helps to open the upper airway and further to move the mandible forward when an infant is sucking on a pacifier (Tonkin S L, Lui D, McIntosh C G, Rowley S, Knight D B, Gunn A J., Effect of Pacifier Use on Mandibular Position in Preterm Infants, Acta Paediatr, 2007, October; 96(10):1433-6. Epub 2007 Aug. 20). Retroposition of mandibles have been considered an additional risk factor for sudden infant death. (Rees K, Facial Structure in the sudden infant death syndrome: case control study, BMJ1998 317:179-180) Forward posturing of the mandible may therefore increase the efficiency of the oral airway. Further Tonkin found that there was significant forward movement of the mandible when premature infants were sucking on a pacifier, and he proposed that the common pathologic mechanism of SIDS was airway occlusion by backward displacement of the tongue and mandible (Tonkin S L et al., Positional upper airways narrowing and an apparent life threatening event, NZ Med J 2002 115:193-4; Tonkin S., Sudden Infant Death Syndrome: Hypothesis of Causation, Pediatrics 1975; 55:650-661).
Further, treatment of airway obstruction by mandibular advancement and distraction osteogenesis, used to eliminate mandibular retrognathia and malposition of the tongue, is also used as a surgical solution for airway obstruction in some cases (Bouchard C., Management of Obstructive Sleep Apnea: Role of Distraction Osteogenesis, Oral Maxillofacial Surg ClinN Am 21 (20090459-475)).
The design of the pacifier shield has largely been based on safety testing/requirements, ease of manufacturing, skin health and moisture retention under shield, handle grip, sized generally “to fit” at different ages, esthetics and marketability. The approximation of the shield against the face, and particularly against the perioral region, can have a restrictive effect on the posturing of the lower jaw during sucking. The retrusive pressure of the shield against the lower perioral region may play an unreported, but significant role in reducing the beneficial effect that infant pacifier sucking has on the airway of the infant. The shield may in fact, discourage a more forward mandibular posture during sucking of the baglet as the shield is pulled back tight against the inferior perioral area; more specifically the anterior mandibular alveolus, erupting mandibular incisors and mandibular symphysis. This inward suck force creates a strong posteriorly-directed pressure of the shield against the mandible.